嗨，我正在完成一個學校專案，如果緊急開關打開，我需要串列項的背景為紅色和白色文本。目前，如果我添加一個帶有緊急開關的專案，串列視圖的所有背景都會發生變化。我在某處看到有人說要使用陣列，但是當我嘗試該代碼塊時它不起作用。提前致謝！
<GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ListView
android:id="@ id/listView"
android:layout_width="match_parent"
android:layout_height="576dp"
android:layout_columnSpan="3"
android:focusableInTouchMode="true"
android:isScrollContainer="true">
</ListView>
<EditText
android:id="@ id/editText"
android:layout_width="209dp"
android:layout_height="wrap_content"
android:layout_weight="0"
android:hint="@string/typeHere"
android:textSize="20dp" />
<Switch
android:id="@ id/switch1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="1"
android:layout_column="1"
android:layout_weight="0"
android:text="@string/urgent" />
<Button
android:id="@ id/buttonAdd"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="1"
android:layout_column="2"
android:layout_weight="0"
android:text="@string/add" />
</GridLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="@ id/to_do_TextView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Testing"
android:textSize="25dp" />
</LinearLayout>
public class MainActivity extends AppCompatActivity {
Button buttonAdd;
Boolean urgent = false;
EditText editText;
ListAdapter adapter;
ListView myListView;
Switch switch1;
ArrayList<String> itemList = new ArrayList<String>( Arrays.asList("Clean Bathroom","Buy Apples","Buy Bananas" ));
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//declare variables
buttonAdd = findViewById(R.id.buttonAdd);
editText = findViewById(R.id.editText);
switch1 = findViewById(R.id.switch1);
ListView myListView = findViewById(R.id.listView);
myListView.setAdapter(adapter = new ListAdapter());
buttonAdd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
itemList.add(editText.getText().toString());
editText.setText("");
//also tried setting value you here and using in getView
if(switch1.isChecked()){
urgent = true;
} else{
urgent = false;
}adapter.notifyDataSetChanged();
}
});
}
// adapter class
class ListAdapter extends BaseAdapter{
@Override
public int getCount() {
return itemList.size();
}
@Override
public Object getItem(int position) {
return itemList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View old, ViewGroup parent) {
View newView =old;
LayoutInflater inflater = getLayoutInflater();
if(newView==null){
newView = inflater.inflate(R.layout.item,parent,false);
}
TextView textview= newView.findViewById(R.id.to_do_TextView);
textview.setText(getItem(position).toString());
if(switch1.isChecked()){
textview.setBackgroundColor(Color.RED);
textview.setText(getItem(position).toString());
}return newView;
}
//to do row class
class ToDoItem {
String name;
Boolean urgent;
}}}
uj5u.com熱心網友回復：
Boolean urgent發生這種情況是因為您對串列中的所有專案使用全域變數。
如果正在使用這樣的類，則需要發送ListAdapter 資訊：urgentStringToDoItem
itemList.add(new ToDoItem(itemList.add(editText.getText().toString()), switch1.isChecked()));
完整的代碼是：
public class MainActivity extends AppCompatActivity {
Button buttonAdd;
EditText editText;
ListAdapter adapter;
ListView myListView;
Switch switch1;
//Create list
ArrayList<ToDoItem> itemList = new ArrayList<>();
//add data
itemList.add(new ToDoItem("Clean Bathroom", false);
itemList.add(new ToDoItem("Buy Apples", false);
itemList.add(new ToDoItem("Buy Bananas", true);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//declare variables
buttonAdd = findViewById(R.id.buttonAdd);
editText = findViewById(R.id.editText);
switch1 = findViewById(R.id.switch1);
ListView myListView = findViewById(R.id.listView);
myListView.setAdapter(adapter = new ListAdapter());
buttonAdd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//Here set to list a item with String and boolean
itemList.add(new ToDoItem(itemList.add(editText.getText().toString()), switch1.isChecked()));
editText.setText("");
adapter.notifyDataSetChanged();
}
});
}
// adapter class
class ListAdapter extends BaseAdapter{
@Override
public int getCount() {
return itemList.size();
}
//Here get a item like ToDoItem
@Override
public ToDoItem getItem(int position) {
return itemList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View old, ViewGroup parent) {
View newView =old;
LayoutInflater inflater = getLayoutInflater();
if(newView==null){
newView = inflater.inflate(R.layout.item,parent,false);
}
TextView textview= newView.findViewById(R.id.to_do_TextView);
//Here get a name
textview.setText(getItem(position).name);
if(getItem(position).urgent){
textview.setBackgroundColor(Color.RED);
}
return newView;
}
}
//Class that have the information on items
class ToDoItem {
String name;
Boolean urgent;
public ToDoItem(String name, Boolean urgent) {
this.name = name;
this.urgent = urgent;
}
}
}
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